I. Field & Utility Summary
The present invention relates to a new and distinct variety of apple tree. The apple tree is particularly useful in that it can be propagated clonally and used as a rootstock or root system for apple trees as well as for interstems of apple trees.
II. Cultivation Summary
‘G.214’ originated from a planned cross in 1975 in Geneva, N.Y.
III. Comparisons
The seed parent Malus domestica ‘Ottawa 3’ is a dwarfing rootstock, i.e., trees grown on this rootstock are 30 to 35 percent the size of a standard tree grafted on an apple seedling rootstock. ‘Ottawa 3’ is known to induce good precocity in the scion (i.e., the ability to induce early reproductive development in the scion) and has high yield efficiency. ‘Ottawa 3’ plants produce no spines, are fairly well anchored, are very cold hardy rootstocks and have resistance to crown and root rot caused by Phytophthora cactorum. However, ‘Ottawa 3’ is susceptible to the woolly apple aphid (Eriosoma lanigerum) and to fire blight (Erwinia amylovora).
The pollen parent Malus robusta ‘Robusta 5’ is a non-dwarfing rootstock, i.e. trees on this rootstock are the same size as a standard tree grafted on an apple seedling rootstock. ‘Robusta 5’ does not induce precocity in the scion and is not highly yield efficient. Juvenile plants of ‘Robusta 5’ produce many spines. ‘Robusta 5’ breaks buds very early in the spring and is winter hardy. It is resistant to powdery mildew (Podosphaera leucotricha) and fire blight, and is immune to the woolly apple aphid. Further, ‘Robusta 5’ has shown tolerance to the specific replant disease complex.
The ‘G.214’ apple rootstock of the present invention has a combination of qualities that distinguishes it from its parental plants (i.e., ‘Ottawa 3’ and ‘Robusta 5’). For example, unlike the well-anchored ‘Ottawa 3’ parent, ‘G.214’ is a poorly anchored rootstock. ‘G.214’ has dwarfing properties derived from ‘Ottawa 3’, and belongs to the same dwarfing vigor class as its dwarfing parent (i.e., ‘Ottawa 3’). Specifically, ‘G.214’ has dwarfing characteristics that are similar to the industry standard of Malus domestica ‘Malling 9’. ‘G.214’ shares further similarities with ‘Ottawa 3’ in that they both induce precocity to the scion, are highly yield efficient, winter hardy, and resistant to crown and root rot caused by Phytophthora cactorum. 
With regard to its ‘Robusta 5’ parent, ‘G.214’ is distinguishable in that it is a dwarfing rootstock and is highly yield efficient, whereas ‘Robusta 5’ is not. However, like ‘Robusta 5’, ‘G.214’ is resistant to fire blight, powdery mildew, and the woolly apple aphid (Eriosoma lanigerum). In addition, ‘G.214’ has been shown to have some tolerance to the replant disease complex.
As discussed above, ‘G.214’ is most similar to ‘Malling 9’ in terms of dwarfing class. However, ‘G.214’ is resistant to fire blight whereas ‘Malling 9’ and other rootstocks in its market class are not.
With regard to apple tree rootstock ‘G.935’, a variety from the same parents as ‘G.214’, ‘G.214’ is resistant to wooly apple aphid (Eriosoma lanigerum)and ‘G.935’ is susceptible.
IV. Breeding History
In the spring of 1975, pollen from a Malus robusta ‘Robusta 5’ apple tree was applied to emasculated flowers of a Malus domestica ‘Ottawa 3’ apple in Geneva, N.Y. In the fall of 1975, approximately 500 seeds resulting from this pollination were extracted from mature fruit derived from this cross. In the winter of 1975-76, the seeds were stratified and planted in large flats under conditions effective to germinate seeds and obtain seedlings. When germinated seedlings were about 2.5 cm tall they were inoculated with a mixture of isolates of the fungus Phytophthora cactorum (the causal agent of crown and root rots). The flats were flooded to mid-hypocotyl level and kept at 23° C. for one week. Surviving seedlings were transplanted into individual pots.
In the summer of 1976, each of the transplanted seedlings was inoculated with approximately 106 colony forming units of the Ea 273 strain of the fire blight bacterium Erwinia amylovora by inserting a 26-gauge hypodermic syringe needle into the shoot tip. The seedling designated as #214 was one of the survivors of this battery of inoculations from the same cross. All the surviving plants were in Geneva, N.Y. in the fall of 1976 and allowed to grow side shoots for propagation/evaluation. In 1978, ‘G.214’ was evaluated for rooting ability, lack of spine production, and low root brittleness in a layering bed (stool bed). In 1982, 4 finished trees with ‘G.214’ rootstock were planted in Geneva, N.Y. with Malus domestica cv. ‘Northern Spy’ grafted onto this rootstock as the scion cultivar. This rootstock performed well (top 20% of many rootstocks tested) in these first test trials and in 1988 more material was propagated by stool bed and nursery to be entered into new trials in Geneva, N.Y. with Malus domestica cv. Empire as the scion cultivar. The ‘G.214’ rootstock performed well with all the scion cultivars that were tested. In August of 2002, several rootstock liners of ‘G.214’ were budded with 15 different scion cultivars to test graft union compatibility the test results showed that ‘G.214’ was compatible with all the cultivars tested. In summer 2002, 40 rootstock liners were inoculated with four different strains of Erwinia amylovora, the fire blight bacterium (ten liners per strain in Geneva, N.Y. As a result, the apple rootstock ‘G.214’ was classified as immune to two of the strains tested and moderately resistant to the other two strains of Erwinia amylovora. 
V. Asexual Reproduction
Asexual reproduction of the ‘G.214’ apple rootstock has been achieved using the traditional method of clonally propagating apple rootstocks. In particular, the original seedling of the ‘G.214’ apple rootstock was planted in Geneva, N.Y. and allowed to develop into a “mother plant.” The ‘G.214’ mother plant was then used to obtain rooted liners using conventional layering procedures. The resulting liners were then planted in a row to generate a layering stool bed (also referred to as the “mother stool bed”). The living tissues (i.e. leaves, stems, roots, buds, and spines) of the mother stool bed were observed to be identical to secondary and tertiary stool bed plants. In addition to conventional layering, the ‘G.214’ apple rootstock variety has been asexually reproduced by root cuttings, by budding and grafting onto seedling and clonal rootstocks, and by tissue culture.
VI. Stability
Observations of trees from these propagations indicate that all trees have proven true to type and identical in all appearances to the original tree.